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          LV06-03-chrdev-06-文件私有数据
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              <table>    <tr>        <td align="center" rowspan="5">PC端开发环境</td>        <td align="center" width=150px>Windows</td>        <td align="left">Windows11</td>    </tr>    <tr>        <td align="center">Ubuntu</td>        <td align="left">Ubuntu20.04.2的64位版本</td>      </tr>    <tr>        <td align="center">VMware® Workstation 17 Pro</td>        <td align="left">17.6.0 build-24238078</td>      </tr>    <tr>        <td align="center">终端软件</td>        <td align="left">MobaXterm(Professional Edition v23.0 Build 5042 (license))</td>    </tr>    <tr>        <td align="center">Win32DiskImager</td>        <td align="left">Win32DiskImager v1.0</td>      </tr>    <tr>        <td align="center" rowspan="3">Linux开发板环境</td>        <td align="center">Linux开发板</td>        <td align="left">正点原子 i.MX6ULL Linux 阿尔法开发板</td>      </tr>    <tr>        <td align="center">uboot</td>        <td align="left">NXP官方提供的uboot，使用的uboot版本为U-Boot 2019.04</td>      </tr>    <tr>        <td align="center">linux内核</td>        <td align="left">linux-4.19.71(NXP官方提供)</td>      </tr></table>
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<details class="folding-tag" blue><summary> 点击查看本文参考资料 </summary>
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              <table>    <tr>        <td align="center">分类</td>        <td align="center">网址</td>        <td align="center">说明</td>    </tr>    <tr>        <td align="center" rowspan="5">官方网站</td>        <td align="left"><a href="https://www.arm.com/" target="_blank">https://www.arm.com/</a></td>        <td align="left">ARM官方网站，在这里我们可以找到Cotex-Mx以及ARMVx的一些文档</td>    </tr>    <tr>        <td align="left"><a href="https://www.nxp.com.cn/" target="_blank">https://www.nxp.com.cn/ </a></td>        <td align="left">NXP官方网站</td>    </tr>    <tr>        <td align="left"><a href="https://www.nxpic.org.cn/" target="_blank">https://www.nxpic.org.cn/</a></td><td align="left">NXP 官方社区</td>    </tr>    <tr>        <td align="left"><a href="https://u-boot.readthedocs.io/en/latest/" target="_blank">https://u-boot.readthedocs.io/en/latest/</a></td><td align="left">u-boot官网</td>    </tr>    <tr>        <td align="left"><a href="https://www.kernel.org/" target="_blank">https://www.kernel.org/</a></td><td align="left">linux内核官网</td>    </tr></table>
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<details class="folding-tag" blue><summary> 点击查看相关文件下载 </summary>
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              <table>    <tr>        <td align="center">分类</td>        <td align="center">网址</td>        <td align="center">说明</td>    </tr>    <tr>        <td align="center" rowspan="3">NXP</td>        <td align="left"><a href="https://github.com/nxp-imx" target="_blank">https://github.com/nxp-imx</a></td>        <td align="left">NXP imx开发资源GitHub组织，里边会有u-boot和linux内核的仓库</td>    </tr>    <tr>        <td align="left"><a href="https://github.com/nxp-imx/linux-imx/releases/tag/v4.19.71" target="_blank">nxp-imx/linux-imx/releases/tag/v4.19.71</a></td>        <td align="left">NXP linux内核仓库tags中的v4.19.71</td>    </tr>    <tr>        <td align="left"><a href="https://github.com/nxp-imx/uboot-imx/releases/tag/rel_imx_4.19.35_1.1.0" target="_blank">nxp-imx/uboot-imx/releases/tag/rel_imx_4.19.35_1.1.0</a></td>        <td align="left">NXP u-boot仓库tags中的rel_imx_4.19.35_1.1.0</td>    </tr>    <tr>        <td align="center" rowspan="2">I.MX6ULL</td>        <td align="left"><a href="https://www.nxp.com.cn/docs/en/data-sheet/IMX6ULLIEC.pdf" target="_blank">i.MX 6ULL Applications Processors for Industrial Products</a></td>        <td align="left">I.MX6ULL 芯片手册（datasheet，可以在线查看）</td>    </tr>    <tr>        <td align="left"><a href="https://www.nxp.com.cn/webapp/Download?colCode=IMX6ULLRM&lang_cd=zh" target="_blank">i.MX 6ULL Applications ProcessorReference Manual</a></td>        <td align="left">I.MX6ULL 参考手册（下载后才能查看，需要登录NXP官网）</td>    </tr>    <tr>        <td align="center" rowspan="2">Source Code</td>        <td align="left"><a href="https://elixir.bootlin.com/linux/latest/source" target="_blank">https://elixir.bootlin.com/linux/latest/source</a></td>        <td align="left">linux kernel源码</td>    </tr>    <tr>        <td align="left"><a href="https://elixir.bootlin.com/u-boot/latest/source" target="_blank">https://elixir.bootlin.com/u-boot/latest/source</a></td>        <td align="left">uboot源码</td>    </tr></table>
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<h1 id="一、概述"><a href="#一、概述" class="headerlink" title="一、概述"></a><font size=3>一、概述</font></h1><p>在之前编写的驱动程序中， 将生成字符设备的一些硬件属性（设备号、 类、 设备名称等） 全都写成了变量的形式， 虽然这样编写驱动代码不会产生报错， 但是会显得有点不专业。通常在驱动开发中会为设备定义相关的设备结构体， 将硬件属性的描述信息全部放在该结构体中， 这一节对设备结构体的功能实现和文件私有数据进行学习。 </p>
<h1 id="二、文件私有数据"><a href="#二、文件私有数据" class="headerlink" title="二、文件私有数据"></a><font size=3>二、文件私有数据</font></h1><p>Linux 中并没有明确规定要使用文件私有数据， 但是在 linux 驱动源码中， 广泛使用了文件私有数据， 这是 Linux 驱动遵循的“潜规则” ， 实际上也体现了 Linux 面向对象的思想。 struct file 结构体中专门为用户留了一个域用于定义私有数据。  我们来看一下：<a target="_blank" rel="noopener" href="https://elixir.bootlin.com/linux/v4.19.71/source/include/linux/fs.h#L920">fs.h - include&#x2F;linux&#x2F;fs.h - <em>struct file</em></a>：</p>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br></pre></td><td class="code"><pre><span class="line"><span class="class"><span class="keyword">struct</span> <span class="title">file</span> &#123;</span></span><br><span class="line">	<span class="comment">// ......</span></span><br><span class="line">	<span class="class"><span class="keyword">struct</span> <span class="title">inode</span>		*<span class="title">f_inode</span>;</span>	<span class="comment">/* cached value */</span></span><br><span class="line">	<span class="type">const</span> <span class="class"><span class="keyword">struct</span> <span class="title">file_operations</span>	*<span class="title">f_op</span>;</span></span><br><span class="line">	<span class="comment">// ......</span></span><br><span class="line">	<span class="comment">/* needed for tty driver, and maybe others */</span></span><br><span class="line">	<span class="type">void</span>			*private_data;</span><br><span class="line">	<span class="comment">// ......</span></span><br><span class="line">&#125;;</span><br></pre></td></tr></table></figure>

<p>文件私有数据的概念在 Linux 驱动中有着非常广泛的应用， 文件私有数据就是将私有数据 private_data 指向设备结构体。 通过它可以将私有数据一路从 open 函数带到 read, write 函数层层传入。 一般是在 open 的时候赋值， read、 write 时使用。 open 函数中私有数据的使用如下所示：  </p>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br></pre></td><td class="code"><pre><span class="line"><span class="class"><span class="keyword">struct</span> <span class="title">device_test</span> <span class="title">dev1</span>;</span></span><br><span class="line"><span class="type">static</span> <span class="type">int</span> <span class="title function_">cdev_test_open</span><span class="params">(<span class="keyword">struct</span> inode *inode, <span class="keyword">struct</span> file *file)</span></span><br><span class="line">&#123;</span><br><span class="line">    file-&gt;private_data = &amp;dev1;</span><br><span class="line">    <span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">&#125;;</span><br></pre></td></tr></table></figure>

<p>在上述代码中， 定义了一个设备结构体 dev1， 然后在 open 函数中， 将私有数据 private_data指向了设备结构体 dev1。我们可以在 read write 函数中通过 private_data 访问设备结构体， 如下所示：  </p>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br></pre></td><td class="code"><pre><span class="line"><span class="type">static</span> <span class="type">ssize_t</span> <span class="title function_">cdev_test_write</span><span class="params">(<span class="keyword">struct</span> file *file,<span class="type">const</span> <span class="type">char</span> _user *buf, <span class="type">size_t</span> size, <span class="type">loff_t</span> *<span class="type">off_t</span>)</span></span><br><span class="line">&#123;</span><br><span class="line">    <span class="class"><span class="keyword">struct</span> <span class="title">device_test</span> *<span class="title">test_dev</span> =</span> (<span class="keyword">struct</span> device_test *)file-&gt;private_data;</span><br><span class="line">    <span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>

<h1 id="三、使用实例"><a href="#三、使用实例" class="headerlink" title="三、使用实例"></a><font size=3>三、使用实例</font></h1><h2 id="1-源码编写"><a href="#1-源码编写" class="headerlink" title="1. 源码编写"></a><font size=3>1. 源码编写</font></h2><h3 id="1-1-chrdev-data-private-demo-c"><a href="#1-1-chrdev-data-private-demo-c" class="headerlink" title="1.1 chrdev_data_private_demo.c"></a><font size=3>1.1 chrdev_data_private_demo.c</font></h3><details class="folding-tag" blue><summary> 点击查看详情 </summary>
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class="keyword">include</span> <span class="string">&lt;linux/module.h&gt;</span> <span class="comment">/* MODULE_LICENSE */</span></span></span><br><span class="line"></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;linux/fs.h&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;linux/cdev.h&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;linux/uaccess.h&gt;</span></span></span><br><span class="line"></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&quot;./timestamp_autogenerated.h&quot;</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&quot;./version_autogenerated.h&quot;</span></span></span><br><span class="line"></span><br><span class="line"><span class="meta">#<span class="keyword">define</span> CHRDEV_NAME <span class="string">&quot;sdev&quot;</span>    <span class="comment">/* 设备名,cat /proc/devices 查看与设备号的对应关系 */</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">define</span> CLASS_NAME  <span class="string">&quot;sclass&quot;</span>  <span class="comment">/* 类名，在 /sys/class 中显示的名称 */</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">define</span> DEVICE_NAME <span class="string">&quot;sdevice&quot;</span> <span class="comment">/* 设备节点名，在 /sys/class/class_name/ 中显示的名称以及 /dev/ 下显示的节点名 */</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">define</span> BUFSIZE     32        <span class="comment">/* 设置最大偏移量为32 */</span></span></span><br><span class="line"></span><br><span class="line"><span class="meta">#<span class="keyword">define</span> CMD_TEST0 _IO(<span class="string">&#x27;S&#x27;</span>, 0)</span></span><br><span class="line"><span class="meta">#<span class="keyword">define</span> CMD_TEST1 _IOW(<span class="string">&#x27;S&#x27;</span>, 1, int)</span></span><br><span class="line"><span class="meta">#<span class="keyword">define</span> CMD_TEST2 _IOR(<span class="string">&#x27;S&#x27;</span>, 2, int)</span></span><br><span class="line"><span class="meta">#<span class="keyword">define</span> CMD_TEST3 _IOW(<span class="string">&#x27;S&#x27;</span>, 3, int)</span></span><br><span class="line"></span><br><span class="line"><span class="class"><span class="keyword">struct</span> __<span class="title">CMD_TEST</span>&#123;</span></span><br><span class="line">	<span class="type">int</span> a;</span><br><span class="line">	<span class="type">int</span> b;</span><br><span class="line">	<span class="type">int</span> c;</span><br><span class="line">&#125;;</span><br><span class="line"></span><br><span class="line"><span class="keyword">typedef</span> <span class="class"><span class="keyword">struct</span> __<span class="title">CHAR_DEVICE</span></span></span><br><span class="line"><span class="class">&#123;</span></span><br><span class="line">    <span class="type">dev_t</span> dev_num;         <span class="comment">// 定义dev_t类型（32位大小）的变量dev_num,用来存放设备号</span></span><br><span class="line">    <span class="class"><span class="keyword">struct</span> <span class="title">cdev</span> <span class="title">s_cdev</span>;</span>    <span class="comment">// 定义cdev结构体类型的变量scdev</span></span><br><span class="line">    <span class="class"><span class="keyword">struct</span> <span class="keyword">class</span> *<span class="keyword">class</span>;</span>   <span class="comment">// 定于struct class *类型结构体变量 class，表示要创建的类</span></span><br><span class="line">    <span class="class"><span class="keyword">struct</span> <span class="title">device</span> *<span class="title">device</span>;</span> <span class="comment">// 设备</span></span><br><span class="line">    <span class="type">char</span> buf[BUFSIZE];     <span class="comment">// 设置数据存储数组mem</span></span><br><span class="line">&#125; _CHAR_DEVICE;</span><br><span class="line"></span><br><span class="line">_CHAR_DEVICE g_sdev;  <span class="comment">//定义一个device_test结构体变量</span></span><br><span class="line"></span><br><span class="line"><span class="type">static</span> <span class="type">int</span> <span class="title function_">sdev_open</span><span class="params">(<span class="keyword">struct</span> inode *inode, <span class="keyword">struct</span> file *file)</span></span><br><span class="line">&#123;</span><br><span class="line">    printk(<span class="string">&quot;This is sdev_open!\n&quot;</span>);</span><br><span class="line">    file-&gt;private_data = &amp;g_sdev;  <span class="comment">//设置私有数据</span></span><br><span class="line">    <span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">&#125;</span><br><span class="line"></span><br><span class="line"><span class="type">static</span> <span class="type">ssize_t</span> <span class="title function_">sdev_read</span><span class="params">(<span class="keyword">struct</span> file *file, <span class="type">char</span> __user *buf, <span class="type">size_t</span> size, <span class="type">loff_t</span> *off)</span></span><br><span class="line">&#123;</span><br><span class="line">    <span class="type">int</span> i = <span class="number">0</span>;</span><br><span class="line">    <span class="type">loff_t</span> offset = *off; <span class="comment">// 将读取数据的偏移量赋值给loff_t类型变量p</span></span><br><span class="line">    <span class="type">size_t</span> count = size;</span><br><span class="line">    _CHAR_DEVICE *pDev=(_CHAR_DEVICE *)file-&gt;private_data; <span class="comment">//在write函数中读取private_data</span></span><br><span class="line"></span><br><span class="line">    <span class="keyword">if</span> (offset &gt; BUFSIZE)</span><br><span class="line">    &#123;</span><br><span class="line">        <span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">    &#125;</span><br><span class="line"></span><br><span class="line">    <span class="keyword">if</span> (count &gt; BUFSIZE - offset)</span><br><span class="line">    &#123;</span><br><span class="line">        count = BUFSIZE - offset;</span><br><span class="line">    &#125;</span><br><span class="line"></span><br><span class="line">    <span class="keyword">if</span> (copy_to_user(buf, pDev-&gt;buf + offset, count))</span><br><span class="line">    &#123; </span><br><span class="line">        <span class="comment">// 将mem中的值写入buf，并传递到用户空间</span></span><br><span class="line">        printk(<span class="string">&quot;copy_to_user error!\n&quot;</span>);</span><br><span class="line">        <span class="keyword">return</span> <span class="number">-1</span>;</span><br><span class="line">    &#125;</span><br><span class="line"></span><br><span class="line">    <span class="keyword">for</span> (i = <span class="number">0</span>; i &lt; BUFSIZE; i++)</span><br><span class="line">    &#123;</span><br><span class="line">        printk(<span class="string">&quot;buf[%d] %c\n&quot;</span>, i, pDev-&gt;buf[i]); <span class="comment">// 将mem中的值打印出来</span></span><br><span class="line">    &#125;</span><br><span class="line">    printk(<span class="string">&quot;read offset is %llu, count is %d\n&quot;</span>, offset, count);</span><br><span class="line">    *off = *off + count; <span class="comment">// 更新偏移值</span></span><br><span class="line"></span><br><span class="line">    <span class="keyword">return</span> count;</span><br><span class="line">&#125;</span><br><span class="line"></span><br><span class="line"><span class="type">static</span> <span class="type">ssize_t</span> <span class="title function_">sdev_write</span><span class="params">(<span class="keyword">struct</span> file *file, <span class="type">const</span> <span class="type">char</span> __user *buf, <span class="type">size_t</span> size, <span class="type">loff_t</span> *off)</span></span><br><span class="line">&#123;</span><br><span class="line">    <span class="type">int</span> i = <span class="number">0</span>;</span><br><span class="line">    <span class="type">loff_t</span> offset = *off; <span class="comment">// 将读取数据的偏移量赋值给loff_t类型变量p</span></span><br><span class="line">    <span class="type">size_t</span> count = size;</span><br><span class="line">    _CHAR_DEVICE *pDev=(_CHAR_DEVICE *)file-&gt;private_data; <span class="comment">//在write函数中读取private_data</span></span><br><span class="line"></span><br><span class="line">    <span class="keyword">if</span> (offset &gt; BUFSIZE)</span><br><span class="line">    &#123;</span><br><span class="line">        <span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">    &#125;</span><br><span class="line"></span><br><span class="line">    <span class="keyword">if</span> (count &gt; BUFSIZE - offset)</span><br><span class="line">    &#123;</span><br><span class="line">        count = BUFSIZE - offset;</span><br><span class="line">    &#125;</span><br><span class="line"></span><br><span class="line">    <span class="keyword">if</span> (copy_from_user(pDev-&gt;buf + offset, buf, count))</span><br><span class="line">    &#123; </span><br><span class="line">        <span class="comment">// 将buf中的值，从用户空间传递到内核空间</span></span><br><span class="line">        printk(<span class="string">&quot;copy_to_user error \n&quot;</span>);</span><br><span class="line">        <span class="keyword">return</span> <span class="number">-1</span>;</span><br><span class="line">    &#125;</span><br><span class="line"></span><br><span class="line">    <span class="keyword">for</span> (i = <span class="number">0</span>; i &lt; BUFSIZE; i++)</span><br><span class="line">    &#123;</span><br><span class="line">        printk(<span class="string">&quot;buf[%d] %c\n&quot;</span>, i, pDev-&gt;buf[i]); <span class="comment">// 将mem中的值打印出来</span></span><br><span class="line">    &#125;</span><br><span class="line">    printk(<span class="string">&quot;write offset is %llu, count is %d\n&quot;</span>, offset, count); <span class="comment">// 打印写入的值</span></span><br><span class="line">    *off = *off + count;                         <span class="comment">// 更新偏移值</span></span><br><span class="line"></span><br><span class="line">    <span class="keyword">return</span> count;</span><br><span class="line">&#125;</span><br><span class="line"></span><br><span class="line"><span class="type">static</span> <span class="type">int</span> <span class="title function_">sdev_release</span><span class="params">(<span class="keyword">struct</span> inode *inode, <span class="keyword">struct</span> file *file)</span></span><br><span class="line">&#123;</span><br><span class="line">    printk(<span class="string">&quot;This is sdev_release!\n&quot;</span>);</span><br><span class="line">    <span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">&#125;</span><br><span class="line"></span><br><span class="line"><span class="type">static</span> <span class="type">loff_t</span> <span class="title function_">sdev_llseek</span><span class="params">(<span class="keyword">struct</span> file *file, <span class="type">loff_t</span> offset, <span class="type">int</span> whence)</span></span><br><span class="line">&#123;</span><br><span class="line">    <span class="type">loff_t</span> new_offset = <span class="number">0</span>; <span class="comment">// 定义loff_t类型的新的偏移值</span></span><br><span class="line">    <span class="keyword">switch</span> (whence)    <span class="comment">// 对lseek函数传递的whence参数进行判断</span></span><br><span class="line">    &#123;</span><br><span class="line">        <span class="keyword">case</span> SEEK_SET:</span><br><span class="line">            <span class="keyword">if</span> (offset &lt; <span class="number">0</span> || offset &gt; BUFSIZE)</span><br><span class="line">            &#123;</span><br><span class="line">                <span class="keyword">return</span> -EINVAL; <span class="comment">// EINVAL=22 表示无效参数</span></span><br><span class="line">            &#125;</span><br><span class="line">            new_offset = offset; <span class="comment">// 如果whence参数为SEEK_SET，则新偏移值为offset</span></span><br><span class="line">            <span class="keyword">break</span>;</span><br><span class="line">        <span class="keyword">case</span> SEEK_CUR:</span><br><span class="line">            <span class="keyword">if</span> ((file-&gt;f_pos + offset &lt; <span class="number">0</span>) || (file-&gt;f_pos + offset &gt; BUFSIZE))</span><br><span class="line">            &#123;</span><br><span class="line">                <span class="keyword">return</span> -EINVAL;</span><br><span class="line">            &#125;</span><br><span class="line">            new_offset = file-&gt;f_pos + offset; <span class="comment">// 如果whence参数为SEEK_CUR，则新偏移值为file-&gt;f_pos + offset，file-&gt;f_pos为当前的偏移值</span></span><br><span class="line">            <span class="keyword">break</span>;</span><br><span class="line">        <span class="keyword">case</span> SEEK_END:</span><br><span class="line">            <span class="keyword">if</span> (file-&gt;f_pos + offset &lt; <span class="number">0</span>)</span><br><span class="line">            &#123;</span><br><span class="line">                <span class="keyword">return</span> -EINVAL;</span><br><span class="line">            &#125;</span><br><span class="line">            new_offset = BUFSIZE + offset; <span class="comment">// 如果whence参数为SEEK_END，则新偏移值为BUFSIZE + offset，BUFSIZE为最大偏移量</span></span><br><span class="line">            <span class="keyword">break</span>;</span><br><span class="line">        <span class="keyword">default</span>:</span><br><span class="line">            <span class="keyword">break</span>;</span><br><span class="line">    &#125;</span><br><span class="line">    file-&gt;f_pos = new_offset; <span class="comment">// 更新file-&gt;f_pos偏移值</span></span><br><span class="line"></span><br><span class="line">    <span class="keyword">return</span> new_offset;</span><br><span class="line">&#125;</span><br><span class="line"></span><br><span class="line"><span class="type">static</span> <span class="type">long</span> <span class="title function_">sdev_ioctl</span><span class="params">(<span class="keyword">struct</span> file *file, <span class="type">unsigned</span> <span class="type">int</span> cmd, <span class="type">unsigned</span> <span class="type">long</span> arg)</span></span><br><span class="line">&#123;</span><br><span class="line">    <span class="type">int</span> val = <span class="number">0</span>;<span class="comment">//定义 int 类型向应用空间传递的变量 val</span></span><br><span class="line">    <span class="keyword">switch</span>(cmd)</span><br><span class="line">    &#123;</span><br><span class="line">        <span class="keyword">case</span> CMD_TEST0:</span><br><span class="line">            printk(<span class="string">&quot;this is CMD_TEST0\n&quot;</span>);</span><br><span class="line">            <span class="keyword">break</span>;</span><br><span class="line">        <span class="keyword">case</span> CMD_TEST1:</span><br><span class="line">            printk(<span class="string">&quot;this is CMD_TEST1\n&quot;</span>);</span><br><span class="line">            printk(<span class="string">&quot;arg is %ld\n&quot;</span>,arg);<span class="comment">//打印应用空间传递来的 arg 参数</span></span><br><span class="line">            <span class="keyword">break</span>;</span><br><span class="line">        <span class="keyword">case</span> CMD_TEST2:</span><br><span class="line">            val = <span class="number">1</span>;<span class="comment">//将要传递的变量 val 赋值为 1</span></span><br><span class="line">            printk(<span class="string">&quot;this is CMD_TEST2\n&quot;</span>);</span><br><span class="line">            <span class="keyword">if</span>(copy_to_user((<span class="type">int</span> *)arg, &amp;val, <span class="keyword">sizeof</span>(val)) != <span class="number">0</span>)</span><br><span class="line">            &#123;</span><br><span class="line">                <span class="comment">//通过 copy_to_user 向用户空间传递数据</span></span><br><span class="line">                printk(<span class="string">&quot;copy_to_user error \n&quot;</span>);</span><br><span class="line">            &#125;</span><br><span class="line">            <span class="keyword">break</span>;</span><br><span class="line">        <span class="keyword">case</span> CMD_TEST3:</span><br><span class="line">        &#123;</span><br><span class="line">            <span class="class"><span class="keyword">struct</span> __<span class="title">CMD_TEST</span> <span class="title">cmd_test3</span> =</span> &#123;<span class="number">0</span>&#125;;</span><br><span class="line">            <span class="keyword">if</span> (copy_from_user(&amp;cmd_test3, (<span class="type">int</span> *)arg, <span class="keyword">sizeof</span>(cmd_test3)) != <span class="number">0</span>)</span><br><span class="line">            &#123;</span><br><span class="line">                printk(<span class="string">&quot;copy_from_user error\n&quot;</span>);</span><br><span class="line">            &#125;</span><br><span class="line">            printk(<span class="string">&quot;cmd_test3.a = %d\n&quot;</span>, cmd_test3.a);</span><br><span class="line">            printk(<span class="string">&quot;cmd_test3.b = %d\n&quot;</span>, cmd_test3.b);</span><br><span class="line">            printk(<span class="string">&quot;cmd_test3.c = %d\n&quot;</span>, cmd_test3.c);</span><br><span class="line">            <span class="keyword">break</span>;</span><br><span class="line">        &#125;</span><br><span class="line">        <span class="keyword">default</span>:</span><br><span class="line">            <span class="keyword">break</span>;</span><br><span class="line">    &#125;</span><br><span class="line"></span><br><span class="line">    <span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">&#125;</span><br><span class="line"></span><br><span class="line"><span class="type">static</span> <span class="class"><span class="keyword">struct</span> <span class="title">file_operations</span> <span class="title">cdev_ops</span> =</span> &#123;</span><br><span class="line">    .owner = THIS_MODULE,<span class="comment">//将owner字段指向本模块，可以避免在模块的操作正在被使用时卸载该模块</span></span><br><span class="line">	.open = sdev_open,</span><br><span class="line">	.read = sdev_read,</span><br><span class="line">	.write = sdev_write,</span><br><span class="line">	.release = sdev_release,</span><br><span class="line">    .llseek = sdev_llseek,</span><br><span class="line">    .unlocked_ioctl = sdev_ioctl,</span><br><span class="line">&#125;; <span class="comment">// 定义file_operations结构体类型的变量g_cdev_dev_ops</span></span><br><span class="line"></span><br><span class="line"><span class="comment">// 模块入口函数</span></span><br><span class="line"><span class="type">static</span> <span class="type">int</span> __init <span class="title function_">chrdev_data_private_demo_init</span><span class="params">(<span class="type">void</span>)</span></span><br><span class="line">&#123;</span><br><span class="line">    <span class="type">int</span> ret;          <span class="comment">// 定义int类型的变量ret，用来判断函数返回值</span></span><br><span class="line">    <span class="type">int</span> major, minor; <span class="comment">// 定义int类型的主设备号major和次设备号minor</span></span><br><span class="line">    printk(<span class="string">&quot;*** [%s:%d]Build Time: %s %s, git version:%s ***\n&quot;</span>, __FUNCTION__,</span><br><span class="line">           __LINE__, KERNEL_KO_DATE, KERNEL_KO_TIME, KERNEL_KO_VERSION);</span><br><span class="line">    printk(<span class="string">&quot;chrdev_data_private_demo module init!\n&quot;</span>);</span><br><span class="line"></span><br><span class="line">    ret = alloc_chrdev_region(&amp;g_sdev.dev_num, <span class="number">0</span>, <span class="number">1</span>, CHRDEV_NAME); <span class="comment">// 自动获取设备号，设备名为chrdev_name</span></span><br><span class="line">    <span class="keyword">if</span> (ret &lt; <span class="number">0</span>)</span><br><span class="line">    &#123;</span><br><span class="line">        printk(<span class="string">&quot;alloc_chrdev_region is error!\n&quot;</span>);</span><br><span class="line">    &#125;</span><br><span class="line">    printk(<span class="string">&quot;alloc_register_region is ok!\n&quot;</span>);</span><br><span class="line">    major = MAJOR(g_sdev.dev_num); <span class="comment">// 使用MAJOR()函数获取主设备号</span></span><br><span class="line">    minor = MINOR(g_sdev.dev_num); <span class="comment">// 使用MINOR()函数获取次设备号</span></span><br><span class="line">    printk(<span class="string">&quot;major is %d, minor is %d !\n&quot;</span>, major, minor);</span><br><span class="line"></span><br><span class="line">    cdev_init(&amp;g_sdev.s_cdev, &amp;cdev_ops); <span class="comment">// 使用cdev_init()函数初始化g_sdev.s_cdev结构体，并链接到g_cdev_dev_ops结构体</span></span><br><span class="line">    g_sdev.s_cdev.owner = THIS_MODULE;          <span class="comment">// 将owner字段指向本模块，可以避免在模块的操作正在被使用时卸载该模块</span></span><br><span class="line">    ret = cdev_add(&amp;g_sdev.s_cdev, g_sdev.dev_num, <span class="number">1</span>); <span class="comment">// 使用cdev_add()函数进行字符设备的添加</span></span><br><span class="line">    <span class="keyword">if</span> (ret &lt; <span class="number">0</span>)</span><br><span class="line">    &#123;</span><br><span class="line">        printk(<span class="string">&quot;cdev_add is error !\n&quot;</span>);</span><br><span class="line">    &#125;</span><br><span class="line">    printk(<span class="string">&quot;cdev_add is ok !\n&quot;</span>);</span><br><span class="line">    g_sdev.class = class_create(THIS_MODULE, CLASS_NAME);          <span class="comment">// 使用class_create进行类的创建，类名称为 class_dev</span></span><br><span class="line">    g_sdev.device = device_create(g_sdev.class, <span class="literal">NULL</span>, g_sdev.dev_num, <span class="literal">NULL</span>, DEVICE_NAME); <span class="comment">// 使用device_create进行设备的创建，设备名称为 device_dev</span></span><br><span class="line"></span><br><span class="line">    <span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">&#125;</span><br><span class="line"></span><br><span class="line"><span class="comment">// 模块出口函数</span></span><br><span class="line"><span class="type">static</span> <span class="type">void</span> __exit <span class="title function_">chrdev_data_private_demo_exit</span><span class="params">(<span class="type">void</span>)</span></span><br><span class="line">&#123;</span><br><span class="line">    <span class="comment">// 需要注意的是， 字符设备的注册要放在申请字符设备号之后，</span></span><br><span class="line">    <span class="comment">// 字符设备的删除要放在释放字符驱动设备号之前。</span></span><br><span class="line">    cdev_del(&amp;g_sdev.s_cdev);                <span class="comment">// 使用cdev_del()函数进行字符设备的删除</span></span><br><span class="line">    unregister_chrdev_region(g_sdev.dev_num, <span class="number">1</span>); <span class="comment">// 释放字符驱动设备号</span></span><br><span class="line">    device_destroy(g_sdev.class, g_sdev.dev_num); <span class="comment">// 删除创建的设备</span></span><br><span class="line">    class_destroy(g_sdev.class);           <span class="comment">// 删除创建的类</span></span><br><span class="line">    printk(<span class="string">&quot;chrdev_data_private_demo exit!\n&quot;</span>);</span><br><span class="line">&#125;</span><br><span class="line"></span><br><span class="line">module_init(chrdev_data_private_demo_init); <span class="comment">// 将__init定义的函数指定为驱动的入口函数</span></span><br><span class="line">module_exit(chrdev_data_private_demo_exit); <span class="comment">// 将__exit定义的函数指定为驱动的出口函数</span></span><br><span class="line"></span><br><span class="line"><span class="comment">/* 模块信息(通过 modinfo chrdev_data_private_demo 查看) */</span></span><br><span class="line">MODULE_LICENSE(<span class="string">&quot;GPL v2&quot;</span>);            <span class="comment">/* 源码的许可证协议 */</span></span><br><span class="line">MODULE_AUTHOR(<span class="string">&quot;sumu&quot;</span>);               <span class="comment">/* 字符串常量内容为模块作者说明 */</span></span><br><span class="line">MODULE_DESCRIPTION(<span class="string">&quot;Description&quot;</span>);   <span class="comment">/* 字符串常量内容为模块功能说明 */</span></span><br><span class="line">MODULE_ALIAS(<span class="string">&quot;module&#x27;s other name&quot;</span>); <span class="comment">/* 字符串常量内容为模块别名 */</span></span><br><span class="line"></span><br></pre></td></tr></table></figure>
              </div>
            </details>

<h3 id="1-2-chrdev-data-private-demo-app-c"><a href="#1-2-chrdev-data-private-demo-app-c" class="headerlink" title="1.2 chrdev_data_private_demo_app.c"></a><font size=3>1.2 chrdev_data_private_demo_app.c</font></h3><details class="folding-tag" blue><summary> 点击查看详情 </summary>
              <div class='content'>
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class="line">121</span><br><span class="line">122</span><br><span class="line">123</span><br><span class="line">124</span><br><span class="line">125</span><br><span class="line">126</span><br><span class="line">127</span><br><span class="line">128</span><br><span class="line">129</span><br><span class="line">130</span><br><span class="line">131</span><br><span class="line">132</span><br><span class="line">133</span><br><span class="line">134</span><br><span class="line">135</span><br><span class="line">136</span><br><span class="line">137</span><br><span class="line">138</span><br><span class="line">139</span><br><span class="line">140</span><br><span class="line">141</span><br><span class="line">142</span><br><span class="line">143</span><br><span class="line">144</span><br><span class="line">145</span><br><span class="line">146</span><br><span class="line">147</span><br><span class="line">148</span><br><span class="line">149</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;stdio.h&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;stdlib.h&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;string.h&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;unistd.h&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;fcntl.h&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;sys/types.h&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;sys/stat.h&gt;</span></span></span><br><span class="line"></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;sys/ioctl.h&gt;</span></span></span><br><span class="line"></span><br><span class="line"><span class="meta">#<span class="keyword">define</span> BUFSIZE   32 <span class="comment">/* 设置最大偏移量为64, 方便打印完整的内存空间数据*/</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">define</span> CMD_TEST0 _IO(<span class="string">&#x27;S&#x27;</span>, 0)</span></span><br><span class="line"><span class="meta">#<span class="keyword">define</span> CMD_TEST1 _IOW(<span class="string">&#x27;S&#x27;</span>, 1, int)</span></span><br><span class="line"><span class="meta">#<span class="keyword">define</span> CMD_TEST2 _IOR(<span class="string">&#x27;S&#x27;</span>, 2, int)</span></span><br><span class="line"><span class="meta">#<span class="keyword">define</span> CMD_TEST3 _IOW(<span class="string">&#x27;S&#x27;</span>, 3, int)</span></span><br><span class="line"></span><br><span class="line"><span class="class"><span class="keyword">struct</span> __<span class="title">CMD_TEST</span>&#123;</span></span><br><span class="line">	<span class="type">int</span> a;</span><br><span class="line">	<span class="type">int</span> b;</span><br><span class="line">	<span class="type">int</span> c;</span><br><span class="line">&#125;;</span><br><span class="line"></span><br><span class="line"><span class="type">static</span> <span class="type">char</span> usrdata[] = &#123;<span class="string">&quot;sumu&quot;</span>&#125;;</span><br><span class="line"></span><br><span class="line"><span class="type">void</span> <span class="title function_">usage_info</span><span class="params">(<span class="type">void</span>)</span></span><br><span class="line">&#123;</span><br><span class="line">	<span class="built_in">printf</span>(<span class="string">&quot;\n&quot;</span>);</span><br><span class="line">	<span class="built_in">printf</span>(<span class="string">&quot;+++++++++++++++++++++++++++++++++++++++++\n&quot;</span>);</span><br><span class="line">	<span class="built_in">printf</span>(<span class="string">&quot;+       help information  @sumu          +\n&quot;</span>);</span><br><span class="line">	<span class="built_in">printf</span>(<span class="string">&quot;+++++++++++++++++++++++++++++++++++++++++\n&quot;</span>);</span><br><span class="line"></span><br><span class="line">	<span class="built_in">printf</span>(<span class="string">&quot;help:\n&quot;</span>);</span><br><span class="line">	<span class="built_in">printf</span>(<span class="string">&quot;use format: ./app_name /dev/device_name arg1 ... \n&quot;</span>);</span><br><span class="line">	<span class="built_in">printf</span>(<span class="string">&quot;            ./chrdev_data_exchange_demo_app.out /dev/sdevice 1 x # 从x位置读取 \n&quot;</span>);</span><br><span class="line">	<span class="built_in">printf</span>(<span class="string">&quot;            ./chrdev_data_exchange_demo_app.out /dev/sdevice 2 x # 从x位置写入 \n&quot;</span>);</span><br><span class="line">	<span class="built_in">printf</span>(<span class="string">&quot;            ./chrdev_data_exchange_demo_app.out /dev/sdevice 3 x # x为任意值 \n&quot;</span>);</span><br><span class="line">    <span class="built_in">printf</span>(<span class="string">&quot;            驱动中buf最大为1024字节 \n&quot;</span>);</span><br><span class="line">	<span class="built_in">printf</span>(<span class="string">&quot;\n&quot;</span>);</span><br><span class="line"></span><br><span class="line">	<span class="built_in">printf</span>(<span class="string">&quot;command info:\n&quot;</span>);</span><br><span class="line">	<span class="built_in">printf</span>(<span class="string">&quot;  (1)load module  : insmod module_name.ko\n&quot;</span>);</span><br><span class="line">	<span class="built_in">printf</span>(<span class="string">&quot;  (2)unload module: rmmod module_name.ko\n&quot;</span>);</span><br><span class="line">	<span class="built_in">printf</span>(<span class="string">&quot;  (3)show module  : lsmod\n&quot;</span>);</span><br><span class="line">	<span class="built_in">printf</span>(<span class="string">&quot;  (4)view device  : cat /proc/devices\n&quot;</span>);</span><br><span class="line">	<span class="built_in">printf</span>(<span class="string">&quot;  (5)create device node: mknod /dev/device_name c major_num secondary_num \n&quot;</span>);</span><br><span class="line">	<span class="built_in">printf</span>(<span class="string">&quot;  (6)show device node  : ls /dev/device_name \n&quot;</span>);</span><br><span class="line">	<span class="built_in">printf</span>(<span class="string">&quot;  (7)show device vlass  : ls /sys/class \n&quot;</span>);</span><br><span class="line">	<span class="built_in">printf</span>(<span class="string">&quot;+++++++++++++++++++++++++++++++++++++++++\n&quot;</span>);</span><br><span class="line">&#125;</span><br><span class="line"></span><br><span class="line"><span class="type">int</span> <span class="title function_">main</span><span class="params">(<span class="type">int</span> argc, <span class="type">char</span> *argv[])</span></span><br><span class="line">&#123;</span><br><span class="line">    <span class="type">int</span> fd = <span class="number">-1</span>;</span><br><span class="line">    <span class="type">int</span> ret = <span class="number">0</span>;</span><br><span class="line">    <span class="type">char</span> *filename = <span class="literal">NULL</span>;</span><br><span class="line">    <span class="type">unsigned</span> <span class="type">int</span> arg1 = <span class="number">0</span>;</span><br><span class="line">    <span class="type">unsigned</span> <span class="type">int</span> arg2 = <span class="number">0</span>;</span><br><span class="line"></span><br><span class="line">    <span class="type">char</span> readbuf[BUFSIZE] = &#123;<span class="number">0</span>&#125;;</span><br><span class="line">    <span class="type">char</span> writebuf[BUFSIZE] = &#123;<span class="number">0</span>&#125;;</span><br><span class="line"></span><br><span class="line">    <span class="type">unsigned</span> <span class="type">int</span> off1 = <span class="number">0</span>; <span class="comment">// 定义读写偏移位置</span></span><br><span class="line">    <span class="type">unsigned</span> <span class="type">int</span> off2 = <span class="number">0</span>; <span class="comment">// 定义读写偏移位置</span></span><br><span class="line">    <span class="type">unsigned</span> <span class="type">int</span> off = <span class="number">0</span>; <span class="comment">// 定义读写偏移位置</span></span><br><span class="line"></span><br><span class="line">    <span class="built_in">printf</span>(<span class="string">&quot;*** Build Time: %s %s,Git Version: %s Git Remote: %s***\n&quot;</span>, </span><br><span class="line">            __DATE__, __TIME__, GIT_VERSION, GIT_PATH);</span><br><span class="line">    <span class="comment">// ./xxx.out /dev/sdevice x x</span></span><br><span class="line">    <span class="keyword">if</span> (argc != <span class="number">4</span>) </span><br><span class="line">    &#123;</span><br><span class="line">        usage_info();</span><br><span class="line">        <span class="keyword">return</span> <span class="number">-1</span>;</span><br><span class="line">    &#125;</span><br><span class="line">    <span class="comment">// 解析参数</span></span><br><span class="line">    filename = argv[<span class="number">1</span>];</span><br><span class="line">    arg1 = atoi(argv[<span class="number">2</span>]);</span><br><span class="line">    arg2 = atoi(argv[<span class="number">3</span>]);</span><br><span class="line">    <span class="built_in">printf</span>(<span class="string">&quot;%s %s %d %d\n&quot;</span>, argv[<span class="number">0</span>], filename, arg1, arg2);</span><br><span class="line"></span><br><span class="line">    <span class="comment">/* 打开驱动文件 */</span></span><br><span class="line">    fd = open(filename, O_RDWR);</span><br><span class="line">    <span class="keyword">if</span> (fd &lt; <span class="number">0</span>)</span><br><span class="line">    &#123;</span><br><span class="line">        <span class="built_in">printf</span>(<span class="string">&quot;can&#x27;t open file %s !\n&quot;</span>, filename);</span><br><span class="line">        <span class="keyword">return</span> <span class="number">-1</span>;</span><br><span class="line">    &#125;</span><br><span class="line"></span><br><span class="line">    off1 = lseek(fd, <span class="number">0</span>, SEEK_END); <span class="comment">// 读取字符设备文件可读写最大的大小</span></span><br><span class="line">    <span class="built_in">printf</span>(<span class="string">&quot;%s mem buf size is %d\n&quot;</span>, filename, off1);</span><br><span class="line">    <span class="keyword">if</span> (arg1 == <span class="number">1</span>)</span><br><span class="line">    &#123; </span><br><span class="line">        off = arg2;<span class="comment">// 获取读写的偏移位置</span></span><br><span class="line">        <span class="comment">/* 从驱动文件读取数据 */</span></span><br><span class="line">        ret = lseek(fd, off, SEEK_SET); <span class="comment">// 将偏移量设置为距离起始地址 off的位置</span></span><br><span class="line">        <span class="keyword">if</span> (ret &lt; <span class="number">0</span>)</span><br><span class="line">        &#123;</span><br><span class="line">            <span class="built_in">printf</span>(<span class="string">&quot;lseek %s %d failed!\n&quot;</span>, filename, off);</span><br><span class="line">        &#125;</span><br><span class="line">        </span><br><span class="line">        ret = read(fd, readbuf, BUFSIZE);</span><br><span class="line">        <span class="keyword">if</span> (ret &lt; <span class="number">0</span>)</span><br><span class="line">        &#123;</span><br><span class="line">            <span class="built_in">printf</span>(<span class="string">&quot;read file %s failed!\n&quot;</span>, filename);</span><br><span class="line">        &#125;</span><br><span class="line">        off2 = lseek(fd, <span class="number">0</span>, SEEK_CUR); <span class="comment">// 读取当前位置的偏移量</span></span><br><span class="line">        <span class="comment">/*  读取成功，打印出读取成功的数据 */</span></span><br><span class="line">        <span class="built_in">printf</span>(<span class="string">&quot;read data \&quot;%s\&quot; from %s! off=%d off2=%d\n&quot;</span>, readbuf, filename, off, off2);</span><br><span class="line"></span><br><span class="line">    &#125;</span><br><span class="line">    <span class="keyword">else</span> <span class="keyword">if</span> (arg1 == <span class="number">2</span>)</span><br><span class="line">    &#123;</span><br><span class="line">        off = arg2;<span class="comment">// 获取读写的偏移位置</span></span><br><span class="line">        ret = lseek(fd, off, SEEK_SET); <span class="comment">// 将偏移量设置为距离起始地址 off的位置</span></span><br><span class="line">        <span class="keyword">if</span> (ret &lt; <span class="number">0</span>)</span><br><span class="line">        &#123;</span><br><span class="line">            <span class="built_in">printf</span>(<span class="string">&quot;lseek %s %d failed!\n&quot;</span>, filename, off);</span><br><span class="line">        &#125;</span><br><span class="line"></span><br><span class="line">        <span class="comment">/* 向设备驱动写数据 */</span></span><br><span class="line">        <span class="built_in">memcpy</span>(writebuf, usrdata, <span class="keyword">sizeof</span>(usrdata));</span><br><span class="line">        ret = write(fd, writebuf, <span class="keyword">sizeof</span>(usrdata));</span><br><span class="line">        <span class="keyword">if</span> (ret &lt; <span class="number">0</span>)</span><br><span class="line">        &#123;</span><br><span class="line">            <span class="built_in">printf</span>(<span class="string">&quot;write file %s failed!\n&quot;</span>, filename);</span><br><span class="line">        &#125;</span><br><span class="line">        off2 = lseek(fd, <span class="number">0</span>, SEEK_CUR); <span class="comment">// 读取当前位置的偏移量</span></span><br><span class="line">        <span class="built_in">printf</span>(<span class="string">&quot;write \&quot;%s\&quot; to %s success!off=%d off2=%d\n&quot;</span>, usrdata, filename, off, off2);</span><br><span class="line">    &#125;</span><br><span class="line">    <span class="keyword">else</span> <span class="keyword">if</span> (arg1 == <span class="number">3</span>)</span><br><span class="line">    &#123;</span><br><span class="line">        <span class="type">int</span> val = <span class="number">0</span>;</span><br><span class="line">        <span class="class"><span class="keyword">struct</span> __<span class="title">CMD_TEST</span> <span class="title">cmd_test3</span> =</span> &#123;<span class="number">2</span>, <span class="number">3</span>, <span class="number">5</span>&#125;;</span><br><span class="line">        ioctl(fd,CMD_TEST0);</span><br><span class="line">        ioctl(fd,CMD_TEST1, <span class="number">1</span>);</span><br><span class="line">        ioctl(fd,CMD_TEST2, &amp;val);</span><br><span class="line">        <span class="built_in">printf</span>(<span class="string">&quot;val = %d\n&quot;</span>, val);</span><br><span class="line"></span><br><span class="line">        ioctl(fd,CMD_TEST3, &amp;cmd_test3);</span><br><span class="line">    &#125;</span><br><span class="line">    <span class="comment">/* 关闭设备 */</span></span><br><span class="line">    ret = close(fd);</span><br><span class="line">    <span class="keyword">if</span> (ret &lt; <span class="number">0</span>)</span><br><span class="line">    &#123;</span><br><span class="line">        <span class="built_in">printf</span>(<span class="string">&quot;can&#x27;t close file %s !\n&quot;</span>, filename);</span><br><span class="line">        <span class="keyword">return</span> <span class="number">-1</span>;</span><br><span class="line">    &#125;</span><br><span class="line"></span><br><span class="line">    <span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>
              </div>
            </details>

<h2 id="2-开发板测试"><a href="#2-开发板测试" class="headerlink" title="2. 开发板测试"></a><font size=3>2. 开发板测试</font></h2><figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta prompt_"># </span><span class="language-bash">加载驱动</span></span><br><span class="line">insmod xxx_demo.ko</span><br><span class="line"><span class="meta prompt_"></span></span><br><span class="line"><span class="meta prompt_"># </span><span class="language-bash">app测试</span></span><br><span class="line">./xxx_demo_app.out /dev/dev_node 3 x # ioctl测试</span><br><span class="line"><span class="meta prompt_"></span></span><br><span class="line"><span class="meta prompt_"># </span><span class="language-bash">卸载驱动</span></span><br><span class="line">rmmod xxx_demo.ko</span><br></pre></td></tr></table></figure>




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    <p><span>文章标题:</span><a href="/post/b83c9d5f.html">LV06-03-chrdev-06-文件私有数据</a></p>
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            minutes     - 0-59之间的整数，做为date对象的分钟数
            seconds     - 0-59之间的整数，做为date对象的秒数
            microseconds - 0-999之间的整数，做为date对象的毫秒数
            ==================================================*/
            var t1 = Date.UTC(2017, 
                              5, 
                              19, 
                              0, 
                              0, 
                              0); //北京时间
            var t2 = Date.UTC(todayYear,todayMonth,todayDate,todayHour,todayMinute,todaySecond);
            var diff = t2-t1;
            var diffYears = Math.floor(diff/years);
            var diffDays = Math.floor((diff/days)-diffYears*365);
            var diffHours = Math.floor((diff-(diffYears*365+diffDays)*days)/hours);
            var diffMinutes = Math.floor((diff-(diffYears*365+diffDays)*days-diffHours*hours)/minutes);
            var diffSeconds = Math.floor((diff-(diffYears*365+diffDays)*days-diffHours*hours-diffMinutes*minutes)/seconds);
            document.getElementById("sitetime").innerHTML="已在这里 "+diffYears+" 年 "+diffDays+" 天 "+diffHours+" 小时 "+diffMinutes+" 分钟 "+diffSeconds+" 秒";
        }
        siteTime();
    </script>



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